1. Field of the Technology
The present invention relates generally to automatic network selection techniques for mobile stations operating in wireless communication networks.
2. Description of the Related Art
For a variety of reasons, a home network operator (e.g. a home public land mobile network or HPLMN in 3GPP parlance) may have a need to dynamically control which networks their subscribers connect to when roaming either in the home country or abroad. For example, the HPLMN operator may have a need to direct its subscribers roaming in country A to be served by network X. This need may arise for commercial reasons, and at certain times it may be beneficial for an operator to ensure that all of their roaming subscribers be directed to one specific network, to ensure that some contractual criteria is met. Another reason is due to network fault conditions. A temporary fault may mean that one network in a given country is unable to offer all of its services to a HPLMN's roaming subscribers. Therefore, the HPLMN operator may have a need to direct its roaming subscribers towards other networks in the country which can offer a full range of service. By way of example, it is not uncommon today for General Packet Radio Service (GPRS) to be temporarily unavailable in a certain Visited PLMN (VPLMN). Yet another reason is based on network load sharing. For example, the HPLMN operator may decide that it wants 40% of its roaming subscribers in a country on network X, 35% on network Y, and 25% on network Z.
The current 3GPP standard specifies that user equipment (UE) shall select the highest priority network as defined in a Preferred PLMN (PPLMN) list stored in a Subscriber Identity Module (SIM) or Universal Subscriber Identity Module (USIM). If dynamic control were to be achieved through use of the PPLMN list, the HPLMN operator would have to update the entire PPLMN list for each subscriber using an over-the-air (OTA) programming mechanism, which requires a large number of Short Message Service (SMS) messages. The large overhead required to update all of the PPLMN lists for the roaming subscribers may be prohibitive. Further; if network load sharing is needed, the HPLMN would have to maintain PPLMN lists on a per subscriber basis. Maintaining such PPLMN lists, however, adds significant overhead with respect to configuration management.
Existing solutions which direct subscribers to a particular network while roaming involve the spoofing of network reject messages by the HPLMN operator when the user equipment makes connection attempts to VPLMNs as per the PPLMN list. The network reject messages are sent via each selected VPLMN until the desired VPLMN, as identified by the HPLMN operator, is reached. Although this technique directs user equipment to specific VPLMNs desired by the HPLMN operator, as apparent it involves a wasteful use of network resources each time such selection is needed.
Accordingly, what are needed are methods and apparatus which overcome the deficiencies of the prior art.